Multifilter Time-series Observations of Eleven Blue Short-period ATLAS Variable Stars

Abstract

Eleven periodic variable stars were observed photometrically through two to four filters from the set UBVR C I C . Phase-folded data for each star cover full cycles of variation. Spectral energy distributions, based on absolute photometry extracted from the literature, are used to inform models of the stars. The stars include four eclipsing systems with hot subdwarfs of spectral type O or B (sdO/B). Periods are in the range 1.8–2.2 hr. Four reflection-effect binaries, with amplitudes as large as 0.5 mag in the R C filter were observed; periods range from 1.6 to 2.4 hr. In two of these latter systems, the primary stars are also sdB stars, while two have white-dwarf components. In all eight of these binaries the companion stars are probably M dwarfs. The remaining three stars are pulsators: one large-amplitude δ Scuti star previously misclassified as an eclipsing system; one field SX Phe star near the Galactic plane; and one multiperiodic high-luminosity star of unknown type. The amplitude is usually a strong function of the wavelength in pulsating stars, but this is not the case for the high-luminosity variable. One possible explanation is that the luminous star has a pulsating companion. The SX Phe and high-luminosity star are both heavily reddened (A V > 5 mag).

Devising a method for determining the aperture brightness of an object using a typical shape of its image

“…The observation conditions were specially selected so that the CCD frames contained a variety of typical shapes of images of the studied variable stars [5]. typical shape of its image on a series of frames.…”

“…7. Determine the size of rectangular IFPA, into which the pixels of the single image of the object under study fall [5].…”

“…The modern methods of astrometry [1] and photometry [2] have been actively used for such a leading direction as asteroid-comet hazard [3]. Most often, photometry [4] includes automatic processing of the results of asteroid/cometary/satellite surveys, as well as the results of observations of variable stars [5]. Massive astro-and photometric catalogs [6], along with archival big data [7], make it possible to obtain knowledge [8] and analyze publicly available data and measurements [9] of celestial objects of the Solar System (OSS) [10].…”